You don't need to specify what type a function takes in Clojure, which is often nice. If you do though, the compiler can sometimes optimize, and make things muc

You don't need to specify what type a function takes in Clojure, which is often nice. If you do though, the compiler can sometimes optimize, and make things much faster. Basically, the compiler does not have to * look up the type of the thing * run the action on it but can instead skip straight to step 2. If you somewhere in your Clojure program (or repl) run (set! warn-on-reflection true) it will print to the console when you are doing reflection. I think it's a good idea to put in the beginning of your core namespace - so that it is always on. Why not always wear the seatbelt when driving, you know?